1. Field of the Invention
This invention relates to improvements in an automatic engine stop and start system for automatically stopping and starting an engine in accordance with the operating conditions.
2. Description of the Prior Art
Some of the motor cars are equipped with automatic engine stop and start systems capable of automatically stopping the engine when the motor car stops at a cross-roads or the like during running through a town and of starting the engine by an ordinary departing operation (depressing of a clutch pedal, for example) at the time of restarting the engine. Equipping the motor cars with such systems as described above makes it possible to reduce the exhaust gases in volume and the consumption of fuel, as the engines are operated when deemed necessary.
To improve the safety, driverability and the like, there are provided conditions on which the automatic stop of the engine is prevented. More specifically, when any of the following data is obtained, the automatic stop of the engine shall not be performed.
(i) When a right turn signal is being issued.
In the case of waiting a right turn at the center of a cross-roads, if the engine is stopped, then restart lacks quick responsiveness. Consequently, this phenomenon is prevented from occurring.
(ii) When a cooler, head lamps, defogger, or a wiper is used.
When the electric energy being used is high the wear of a battery becomes heavy, whereby it becomes difficult to restart the engine. Consequently, this phenomenon is prevented from occurring.
(iii) When the temperature of the engine cooling water is off.
When the engine is stopped in a condition close to an overheat, it becomes difficult to restart the engine. Consequently, this phenomenon is prevented.
(iv) When an accelerator pedal is depressed, or when a clutch pedal is slightly depressed, while the vehicle is stopped after the automatic engine stop and start system has been set.
This is a measure for not losing the quick responsiveness when the stopping time is very short such for example as a temporary stop at a cross-roads where a traffic signal is working and a temporary stop during slow running condition.
Out of the above-described reasons for preventing the automatic engine stops, the prevention of the automatic engine stop by a thermosensor at a high temperature (105.degree. C. or more, for example) of the engine cooling water is aimed at the protection for components and parts due to the ill effect of heat. However, the generation of ill effect of heat of the temperature of the engine cooling water is not limited to the high temperature range but reaches a wide temperature range. For example, measures are required even in the low temperature range for remedying the problem of restart of the engine.